I don't understand ?
The 'level playing field' simply doesn't exist.
If you take 2 well-matched individual athletes and give them an identical amount of an identical drug the effect on each athlete will be different due to their unique physiology. In this instance the drug (EPO) could give athlete 1 (you) a 2% boost to their performance. It might give athlete 2 (me) a 10% boost to my performance. So, even though we're well-matched at the start and take the same drugs I'll get a greater performance boost. It could even be that you're better than me beforehand, but because we've both been given the same drug I come out on top afterward.
It isn't the case that 'best athlete before drugs' = 'best athlete with drugs'.